The goal of this research proposal is to explore the role of cadherins in retinotectal laminar patterning and synapse formation. The chick retinotectal system provides a well defined projection to a distinctly laminated structure that is experimentally accessible, molecularly well characterized, and able to be explored in culture. Previous experiments suggested that N-cadherin is involved in retinotectal synapse formation and that multiple other cadherins are found in the optic tectum. This project will focus on identifying those cadherins, generating additional reagents to study them, examining their laminar distribution (with particular emphasis on the role of synaptic inputs in generating the patterns of expression), and, where appropriate, exploring their function both in vitro using a retinotectal coculture developed in the Sanes lab and in vivo using surgical manipulations and viral vectors to misexpress genes.